test 4 notes 7 - Antiviral Therapy

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Antiviral Therapy http://aidsinfo.nih.gov/contentfiles/HIVandItsTreatment_cbrochure_en.pdf Antiviral agents are much fewer in number than antibacterial agents. In this section we will discuss drugs used to treat herpes, influenza and human immunodeficiency virus (HIV). HIV is particularly challenging to treat because as the virus reproduces itself, different strains of the virus emerge, some that are resistant to antiretroviral drugs. Therefore, it is recommended that patients infected with HIV take a combination of antiretroviral drugs known as HAART (Highly Active Antiretroviral Therapy). A basic understanding of these drugs is encouraged although consultation with an HIV specialist is necessary to design an effective HAART regimen. List of Nucleoside Analogues for Herpesvirus Infections acyclovir (Zovirax) famciclovir ( Famvir ) valacyclovir (Valtrex) Pharmacodynamics of the Nucleoside Analogues for Herpesvirus Infections These drugs are activated by several enzyme-controlled mechanisms. The first of these is by a virus-specified enzyme that is only present in cells infected by the virus. The second two steps are controlled by enzymes inherently present in the infected (host) cell. This series of enzyme mechanisms insure that the drugs are only active in infected cells and not in non-infected cells. When they become activated, they, in turn, block an enzyme in the infected cells (viral DNA polymerase) that is necessary for the viral particles to replicate themselves. These drugs are active primarily against herpes simplex viruses (HSV-1 and HSV-2) and against the varicella-zoster virus (VZV). Other viruses that are somewhat inhibited are the Ebstein-Barr virus (EBV) and the hepatitis B virus. Pharmacokinetics of the Nucleoside Analogues for Herpesvirus Infections All of the anti-herpes drugs are administered orally and well absorbed by this route. Acyclovir is also available as a topical ointment and I.V. All undergo some degree of hepatic metabolism; valacyclovir is metabolized and converted into acyclovir and famciclovir is a prodrug that is converted into another anti-herpes compound, penciclovir. They are all excreted in the urine. Advantages of Using the Nucleoside Analogues for Herpesvirus Infections ACYCLOVIR - Available in multiple formulations; oral, topical, and I.V. 1
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Antiviral Therapy - Multiple clinical applications for various disease conditions caused by susceptible viruses; labial herpes, genital herpes, shingles , chicken-pox, HSV proctitis, herpes encephalitis - Useful for both primary infection and recurrent viral infections with susceptible viruses - Can be used as prophylaxis in labial HSV-1 and HSV-2 - Minimal adverse effects - Generic form is available - Topical form useful to minimize systemic effects when treating cutaneous conditions FAMCICLOVIR AND VALACYCLOVIR - Available orally (tablets and suspension) - Activity against HSV and VZV - Minimal adverse effects - Less frequent dosing than acyclovir; requires only q8h to q12h dosing
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This note was uploaded on 05/19/2011 for the course NURSING 517/617 taught by Professor Lipstate during the Spring '11 term at University of Louisiana at Lafayette.

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test 4 notes 7 - Antiviral Therapy

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